Gene expression profiling of human livers during normothermic machine perfusion

Normothermic machine perfusion (NMP) has been successfully implemented in clinical routine of liver transplantation over the past years. However, little is known about the mechanisms how NMP impacts on the transcriptome of a human donor liver. We herein examined gene expression profiles in transplanted and non-transplanted livers over NMP time. 50 livers subjected to NMP were included in this study. 30 were transplanted after a maximum of 20 hours (h) perfusion, while 15 were discarded due to poor performance. Biopsies were collected befor eNP (PRE), 1h, 6h, 12h, 20h of NMP and after reperfusion. Next-generation sequencing was applied in liver biopsies to assess differential gene expression over perfusion time. Perfusate samples were collected regularly to monitor liver function. Comparison in differential gene expression between PRE and 20h NMP showed 415 upregulated and 727 downregulated genes. Most significantly upregulated genes were associated with extra cellular matrix organization, cell growth/differentiation processes and cytokine signaling. A set of genes were identified which were significantly differentially expressed and important for classification of non-transplanted vs transplanted biopsies, especially at 12 and 20h of NMP. A 7-gene-signature showed good separation already at 6H NMP, thereby CD274 (PD-L1) expression was ponted out as most important.